Simplify message parsing.

remoting/protocol/channel_dispatcher_base.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef REMOTING_PROTOCOL_CHANNEL_DISPATCHER_BASE_H_
 #define REMOTING_PROTOCOL_CHANNEL_DISPATCHER_BASE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 37 matching lines @@
 
   const std::string& channel_name() { return channel_name_; }
 
   // Returns true if the channel is currently connected.
   bool is_connected() { return channel_ != nullptr; }
 
  protected:
   explicit ChannelDispatcherBase(const char* channel_name);
 
   BufferedSocketWriter* writer() { return &writer_; }
-  MessageReader* reader() { return &reader_; }
+
+  // Should be overridden in child classes to handle incoming messages.
+  virtual void OnIncomingMessage(scoped_ptr<CompoundBuffer> message);

[Jamie, 2016/01/30 00:56:27]

Is the case for not overriding this sufficiently common to warrant it being
non-pure-virtual? If it's rare, I think I'd prefer this to be pure-virtual with
explicit no-op overrides where appropriate.

If it's common, then default handling in the base class makes sense (though I'd
argue that "may" would be more appropriate than "should" in the comment in that
case).

[Sergey Ulanov, 2016/01/30 02:15:48]

Some channels are one-directional (events and audio). The dispatcher on the
sending side doesn't need to override this method.
Anyway, I don't care one way or the other. Made it pure virtual.

 
  private:
   void OnChannelReady(scoped_ptr<P2PStreamSocket> socket);
   void OnReadWriteFailed(int error);
 
   std::string channel_name_;
   StreamChannelFactory* channel_factory_;
   EventHandler* event_handler_;
   scoped_ptr<P2PStreamSocket> channel_;
 
   BufferedSocketWriter writer_;
   MessageReader reader_;
 
   DISALLOW_COPY_AND_ASSIGN(ChannelDispatcherBase);
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_CHANNEL_DISPATCHER_BASE_H_